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1/* SPDX-License-Identifier: GPL-2.0-or-later */
2
3#ifndef _NET_GSO_H
4#define _NET_GSO_H
5
6#include <linux/skbuff.h>
7
8/* Keeps track of mac header offset relative to skb->head.
9 * It is useful for TSO of Tunneling protocol. e.g. GRE.
10 * For non-tunnel skb it points to skb_mac_header() and for
11 * tunnel skb it points to outer mac header.
12 * Keeps track of level of encapsulation of network headers.
13 */
14struct skb_gso_cb {
15 union {
16 int mac_offset;
17 int data_offset;
18 };
19 int encap_level;
20 __wsum csum;
21 __u16 csum_start;
22 /* Number of IPv4/IPv6 GSO handler entries for this packet. */
23 u8 recursion_counter;
24};
25#define SKB_GSO_CB_OFFSET 32
26#define SKB_GSO_CB(skb) ((struct skb_gso_cb *)((skb)->cb + SKB_GSO_CB_OFFSET))
27
28static inline bool gso_recursion_inc_test(struct sk_buff *skb,
29 unsigned int limit)
30{
31 return ++SKB_GSO_CB(skb)->recursion_counter > limit;
32}
33
34static inline int skb_tnl_header_len(const struct sk_buff *inner_skb)
35{
36 return (skb_mac_header(inner_skb) - inner_skb->head) -
37 SKB_GSO_CB(inner_skb)->mac_offset;
38}
39
40static inline int gso_pskb_expand_head(struct sk_buff *skb, int extra)
41{
42 int new_headroom, headroom;
43 int ret;
44
45 headroom = skb_headroom(skb);
46 ret = pskb_expand_head(skb, extra, 0, GFP_ATOMIC);
47 if (ret)
48 return ret;
49
50 new_headroom = skb_headroom(skb);
51 SKB_GSO_CB(skb)->mac_offset += (new_headroom - headroom);
52 return 0;
53}
54
55static inline void gso_reset_checksum(struct sk_buff *skb, __wsum res)
56{
57 /* Do not update partial checksums if remote checksum is enabled. */
58 if (skb->remcsum_offload)
59 return;
60
61 SKB_GSO_CB(skb)->csum = res;
62 SKB_GSO_CB(skb)->csum_start = skb_checksum_start(skb) - skb->head;
63}
64
65/* Compute the checksum for a gso segment. First compute the checksum value
66 * from the start of transport header to SKB_GSO_CB(skb)->csum_start, and
67 * then add in skb->csum (checksum from csum_start to end of packet).
68 * skb->csum and csum_start are then updated to reflect the checksum of the
69 * resultant packet starting from the transport header-- the resultant checksum
70 * is in the res argument (i.e. normally zero or ~ of checksum of a pseudo
71 * header.
72 */
73static inline __sum16 gso_make_checksum(struct sk_buff *skb, __wsum res)
74{
75 unsigned char *csum_start = skb_transport_header(skb);
76 int plen = (skb->head + SKB_GSO_CB(skb)->csum_start) - csum_start;
77 __wsum partial = SKB_GSO_CB(skb)->csum;
78
79 SKB_GSO_CB(skb)->csum = res;
80 SKB_GSO_CB(skb)->csum_start = csum_start - skb->head;
81
82 return csum_fold(csum_partial(csum_start, plen, partial));
83}
84
85struct sk_buff *__skb_gso_segment(struct sk_buff *skb,
86 netdev_features_t features, bool tx_path);
87
88static inline struct sk_buff *skb_gso_segment(struct sk_buff *skb,
89 netdev_features_t features)
90{
91 return __skb_gso_segment(skb, features, true);
92}
93
94struct sk_buff *skb_eth_gso_segment(struct sk_buff *skb,
95 netdev_features_t features, __be16 type);
96
97struct sk_buff *skb_mac_gso_segment(struct sk_buff *skb,
98 netdev_features_t features);
99
100bool skb_gso_validate_network_len(const struct sk_buff *skb, unsigned int mtu);
101
102bool skb_gso_validate_mac_len(const struct sk_buff *skb, unsigned int len);
103
104static inline void skb_gso_error_unwind(struct sk_buff *skb, __be16 protocol,
105 int pulled_hlen, u16 mac_offset,
106 int mac_len)
107{
108 skb->protocol = protocol;
109 skb->encapsulation = 1;
110 skb_push(skb, pulled_hlen);
111 skb_reset_transport_header(skb);
112 skb->mac_header = mac_offset;
113 skb->network_header = skb->mac_header + mac_len;
114 skb->mac_len = mac_len;
115}
116
117#endif /* _NET_GSO_H */